Phase 3 Study Comparing Inavolisib Plus Phesgo Versus Placebo Plus Phesgo as Maintenance Therapy for PIK3CA-Mutated HER2-Positive Advanced Breast Cancer

What this Trial Is About

Researchers are evaluating the effectiveness and safety of inavolisib combined with Phesgo compared to a placebo combined with Phesgo as maintenance treatment for participants with previously untreated HER2-positive advanced breast cancer that has a PIK3CA mutation. This Phase 3 study focuses on participants with locally advanced or metastatic breast cancer who have completed induction therapy. Participants first receive induction therapy with Phesgo plus taxane-based chemotherapy. Following this, they enter the maintenance phase where they are randomly assigned to receive either inavolisib tablets taken orally once daily for 21 days of each 21-day cycle along with Phesgo administered subcutaneously every 3 weeks, or a matching placebo tablet with Phesgo on the same schedule. Optional endocrine therapy may be given based on the investigators choice according to standard care. Throughout the study, participants undergo regular monitoring including tumor assessments, quality of life questionnaires, and safety evaluations lasting up to approximately 111 months. Key outcomes measured include progression-free survival assessed by investigators, overall survival, response rates, duration of response, and adverse event rates. Plasma concentrations of inavolisib are also measured at specific timepoints. Participants will be followed closely during and after treatment to assess these outcomes over an extended period.

A Study to Evaluate the Efficacy and Safety of Inavolisib in Combination With Phesgo Versus Placebo in Combination With Phesgo in Participants With PIK3CA-Mutated HER2-Positive Locally Advanced or Metastatic Breast Cancer